An-Di Yim

AN-DI YIM, then a graduate student at University of Illinois, Urbana, Illinois, was awarded a grant in May 2019 to aid research on ‘Ontogeny, Evolution and Ecogeographic Patterns of Human Limb Morphology,’ supervised by Dr. Charles Roseman. Modern humans expanded into nearly every region of the world, adapting both culturally and biologically to a range of natural environments. Past research in human skeletal biology has shown that the human limb skeleton shifts toward a shorter, more robust morphology in cold-adapted populations and a taller, less robust morphology in heat-adapted populations. This project examined how evolutionary processes have shaped this diversity in the human limb skeleton through changes in growth and development (ontogeny). Using a global sample of osteometric measurements taken from bone specimens of archaeological groups and 3D modules reconstructed from CT scans of contemporary groups, this research teases apart these different evolutionary forces by first showing that the relationship between overall body size and various skeletal traits represented by linear measurements will be conserved among different groups and across age. A linear mixed-effects model was built to study the ontogenetic trajectories of the dimensions of the limb skeleton. The results show population structure arising from neutral evolution, the allometric variation associated with the change in size, and directional effects from climatic factors all contributed to the variation in ontogenetic trajectories of all major long bone dimensions in modern humans.